Brain Pathology Case of the Month - June 2013

A 30-year-old Chinese male presented with an 8 week history of headaches, visual changes, lightheadedness and balance problems. These symptoms were attributed to increased intracranial pressure secondary to obstructive hydrocephalus. Computed tomography (CT) scans demonstrated an iso-or slightly hyperdense mass within both lateral ventricles. The septum pellucidum was not seen well on imaging studies and the tumor was centered on the midline. Contrast enhancement was mild to moderate. An MRI scan revealed a large midline mass obliterating large portions of the lateral ventricles and giving rise to obstructive hydrocephalus and transependymal edema. The mass was isointense on T1 weighted imaging and contained calcification On T2 weighted images it was relatively isointense with cortex (Fig. 1 and Fig. 2). There was moderate enhancement after the administration of gadolinium. Postoperative MRI scan showed gross total resection and some blood. After radiotherapy, the nerval symptoms had lapse to. But repeated MRI scans in the following 12 months showed recrudescence in the MRI findings and patient had more nerval symptomatic. Finally, the patient died of hydrocephalus and brain edema 20 months after the surgery.

GROSS PATHOLOGY

The operative specimen was a broken tissue which had a lobulated, well-circumscribed, gray-colored mass, 5 cm×4cm×3 cm, soft in character, attend by intratumoral hemorrhage and putrescence.

MICROSCOPIC PATHOLOGY

Microscopic examination showed sheets of monotonously small- to medium-sized neoplastic cells with uniform round-to-oval nuclei and inconspicuous nucleoli. The nuclei were surrounded by perinuclear halos. Cellular borders were indistinct and cells appeared to contain a moderate amount of amphophilic cytoplasm. The tumor cells were dense in some areas and alternate with anuclear, less dense tumor parts. And the anuclear areas had a fine fibrillary matrix. Delicate vasculature formed a branching network in a pattern similar to oligodendroglioma. Focal calcification can be seen. The remarkable characteristic was that there were mitoses, nuclear atypia, necrosis and microvascular proliferation (Figs. 3, 4, 5).

Tumor cells had strong cytoplasmic reactivity for NSE (Fig. 6), NeuN (Fig. 7), Synaptophysin, and CD99. A few entrapped astrocytes reacted appropriately with GFAP, but the tumor cells were negative. The MIB-1 (Ki67) labeling index was estimated at 10% in all areas (Fig. 8)